NH4I-Promoted and H2O-Controlled Intermolecular Bis-sulfenylation and Hydroxysulfenylation of Alkenes via a Radical Process

TCT-Mediated and Water-Controlled Synthesis of Benzofuran-3(2H)-ones Bearing a Quaternary Carbon Center via a Radical Process Using Dimethyl Sulfoxide as a Dual Synthon

An efficient and attractive method for the synthesis of valuable benzofuran-3(2H)-one derivatives bearing a quaternary center in one step by employing dimethyl sulfoxide (DMSO) as a dual synthon under metal-free conditions has been developed. In this reaction, DMSO activated by cyanuric chloride (TCT) provides two different units (CH3 and SMe) in the target molecules, and the construction of the quaternary carbon center in the benzofuran-3(2H)-ones can be controlled by the addition of water. Furthermore, the functional group compatibility and synthetic value were demonstrated by scope evaluation and gram-scale experiments. The mechanistic studies show that the reaction may proceed via a radical process.

Cobalt-catalyzed dithiolation of unactivated alkenes with thiols: facile access to diverse vicinal dithioethers

Direct dithiolation of alkenes with thiols has been rarely reported. Herein, a simple cobalt-catalyzed aerobic approach has been developed to realize this transformation. With the aid of HFIP, diverse vicinal dithioethers including symmetric and unsymmetric ones could be obtained from readily available substrates. Gram-scale synthesis and late-stage modification of complex molecules highlight the practicability of this approach.

Ring-Closing Disulfenylation of Alkenoic Thioester

This study demonstrated for the first time that alkenoic thioesters can be effectively used as nucleophiles in ring-closing disulfenylation reactions. Our investigation revealed that the reaction in hexafluoroisopropanol with an electrophilic sulfur reagent significantly enhances the product yield. We gathered experimental and theoretical evidence to support the superiority of thioesters over the traditionally used benzyl sulfide. Additionally, we explored the substrate scope and identified various factors affecting the reaction selectivity and yield.

Synthesis of β-Hydroxysulfides via Multi-Component Cascade Hydroxysulfenylation of Styrenes with NH4 SCN and Water under Transition-metal-free Conditions

Transition-mental-free multi-component hydroxysulfenylation of styrenes with NH4 SCN and water to from β-hydroxysulfides is established. The reaction mechanism proceeded via a domino reaction after a radical addition to 2-phenylimidazo[1,2-a]pyridines. This approach features a wide substrate scope and functional group compatibility, providing 34 compounds in acceptable yields.

Green Approach for the Synthesis of Chalcogenyl- 2,3-dihydrobenzofuran Derivatives Through Allyl-phenols/ Naphthols and Their Potential as MAO-B Inhibitors

This work presents the design, synthesis, and MAO-B inhibitor activity of a series of chalcogenyl-2,3-dihydrobenzofurans derivatives. Using solvent- and metal-free methodology, a series of chalcogen-containing dihydrobenzofurans 7-9 was obtained with yields ranging from 40% to 99%, using an I2 /DMSO catalytic system. All compounds were fully structurally characterized using 1 H and 13 C NMR analysis, and the unprecedented compounds were additionally analyzed using high-resolution mass spectrometry (HRMS). In addition, the mechanistic proposal that iodide is the most likely species to act in the transfer of protons along the reaction path was studied through theoretical calculations. Finally, the compounds 7b-e, 8a-e, and 9a showed great promise as inhibitors against MAO-B activity.

Aromatization of cyclic hydrocarbons via thioether elimination reaction

Herein, the diversity-oriented aromatization of cyclic hydrocarbons via potassium ethyl xanthogenate (EtOCS2K)/NH4I-mediated methylthiyl radical addition and thioether elimination was investigated under transition-metal-free conditions. The methylthiyl radical species were generated in situ via the NH4I-mediated decomposition of DMSO following which EtOCS2K promoted the breaking of carbon-sulfur bonds of thioether.

Selectfluor-Promoted Reactions of Aryl Methyl Ketones with Dimethyl Sulfoxide to Give 2,5-Diacylthiophenes and β-Acyl Allylic Methylsulfones

In this paper, a convenient synthesis of 2,5-diacylthiophenes and β-acyl allylic methylsulfones from aryl methyl ketones with dimethyl sulfoxide (DMSO) through Selectfluor-promoted cascade cyclization and cross-coupling reactions by simple solvent modification is described. This method enables the formation of new C-C and C-S bonds via the selection of different solvent ratios, in which DMSO molecules as synthons can be selectively introduced into methyl ketones. The features of this transformation include readily available starting materials, excellent chemoselectivity, and good functional group tolerance.

Intermolecular difunctionalization of alkenes: synthesis of β-hydroxy sulfides

Direct difunctionalization of carbon-carbon double bonds is one of the most powerful tools available for concomitant introduction of two functional groups into olefinic substrates. In this context, vicinal hydroxysulfenylation of unactivated alkenes has emerged as a novel and straightforward strategy for the fabrication of β-hydroxy sulfides, which are extremely valuable starting materials in constructing various natural products, pharmaceuticals, and fine chemicals. The aim of this review is to summarize the most representative and important reports on the preparation of β-hydroxy sulfides through intermolecular hydroxysulfenylation of the corresponding alkenes with special emphasis on the mechanistic features of the reactions.

NIS-promoted intermolecular bis-sulfenylation of allenamides via a two-step radical process: synthesis of 1,3-dithioethers

The first report of NIS-promoted two-step radical addition of thiols to allenamides to provide an efficient route for accessing 1,3-dithioethers.

Access to 4-substituted isothiazoles through three-component cascade annulation and their application in C–H activation

The use of EtOCS₂k enabled the annulation of isopropene derivatives with NH₄I, affording various 4-substituted isothiazoles in good yields.

Photoredox β-thiol-α-carbonylation of enones accompanied by unexpected Csp2–C(CO) bond cleavage

An olefinic difunctionalization method of enones was presented here via aerobic visible-light catalysis.

(Z)-Tetrahydrothiophene and (Z)-tetrahydrothiopyran synthesis through nucleophilic substitution and intramolecular cycloaddition of alkynyl halides and EtOCS2K

This protocol provides a novel, environmentally friendly and simple method for the synthesis of (Z)-tetrahydrothiophene derivatives using the nucleophilic thiyl radical intramolecular cycloaddition cascade process to construct C-S bonds under transition-metal-free conditions. This transformation process offers a broad substrate scope, good functional group tolerance, and excellent stereoselectivity (Z/E ratios up to 99/1). Moreover, the process uses odourless, stable and cheap EtOCS2K as the sulfur source.